When to plant Lobelia in Juneau City and Borough County,
Juneau City and Borough County's 152-day season only supports one Lobelia planting per year. Sow between April 12 and April 26 for the best chance at full maturity before October 2.
When to Plant Lobelia in Juneau City and Borough, AK
This month in Juneau City and Borough, Alaska
Welcome to June in Zone 7a. These are the moves that will have the biggest impact on your growing season.
-
Basket week: lobelia
Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.
Before July arrives, get these ready
- Starting indoors: lobelia
- First harvests: lobelia
Lobelia (Lobelia erinus) is a cool-season annual prized for the intense cobalt blue that is rare among bedding flowers. It blooms most prolifically in spring and early summer but stalls or dies back during heat peaks above 90°F. In zones 3–7 it delivers a long display; in zones 8–9 it is best treated as a spring annual that fades by midsummer. Trailing types cascade beautifully from containers and window boxes.
Juneau City and Borough, Alaska is in USDA Zone 7a. The average last spring frost is May 3 and the first fall frost is October 2, giving you a growing season of approximately 152 days.
At an elevation of 930 feet, Juneau City and Borough receives approximately 35.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 57°F, so choose short-season varieties of Lobelia to ensure they mature before fall.
Juneau City and Borough Soil Profile
Soil Type
Silt Loam
Soil pH
5.1-6.5
Drainage
Well Drained
Lobelia Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Soil Compatibility in Juneau City and Borough
How your county's soil matches Lobelia's growing requirements.
Soil pH
Your soil pH (5.1–6.5) is more acidic than Lobelia prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Juneau City and Borough is excellent for Lobelia — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (6.7%) — Lobelia will thrive.
How to Plant Lobelia
Succession Planting Lobelia
Sow every 8 weeks. Last sowing by Jul 14 to harvest before frost.
Lobelia Water Budget
Monthly Watering Guide for Lobelia
Lobelia needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Lobelia Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 1.3" | 0" | ❄️ Dormant |
| Apr | — | 1" | 0" | ❄️ Dormant |
| May | 4.3" | 1.6" | 2.7" | 🚿 Regular watering |
| Jun | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| Jul | 4.3" | 4.4" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 5.3" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 6.5" | 0" | ✅ Rainfall sufficient |
| Oct | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Nov | — | 2.7" | 0" | ❄️ Dormant |
| Dec | — | 2.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Juneau City and Borough). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Lobelia Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Lobelia Planting Timeline — Juneau City and Borough, AK
Lobelia Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 1 | Mar 1 – Mar 15 |
| Transplant Outdoors | April 12 | Apr 12 – Apr 26 |
| Bloom | June 7 | Jun 7 – Aug 30 |
· 6" apart · Rows 8" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors |
| May | — |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
70–80 days
🧪 Soil pH
Needs 6–7 · Your soil: too_acidic
🗺️ USDA Zone
Zone 7a
📆 Growing Season
152 days in Juneau City and Borough
Growing Tips for Lobelia in Juneau City and Borough
Direct sow Lobelia outdoors after May 03 in Juneau City and Borough when soil has warmed and frost danger has passed.
General growing tips
Start seeds indoors 10–12 weeks before last frost — seed is dust-fine and requires light to germinate; surface-sow and press gently. Keep at 65–70°F. Not reliably direct-sown. Transplant in cool weather, 2–4 weeks before last frost date is acceptable in zones 5+. Shear plants by one-third after the first bloom flush to encourage a second flush in fall. Provide afternoon shade in zones 7+ to extend bloom into summer.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Lobelia in Other Locations
Frequently Asked Questions
When should I plant Lobelia in Juneau City and Borough, AK?
Juneau City and Borough is in Zone 7a with an average last frost of May 3. Plan your Lobelia planting based on this frost date — see the calendar above for exact timing.
What planting zone is Juneau City and Borough, AK?
Juneau City and Borough, Alaska is in USDA Hardiness Zone 7a. The average last spring frost is May 3 and first fall frost is October 2.
When should I plant Lobelia in Juneau City and Borough County, ?
In Juneau City and Borough County, , plant Lobelia after the last frost (around May 3) and before the first frost (around October 2). Best results when soil holds above 50°F.
What growing zone is Juneau City and Borough County, for Lobelia?
Juneau City and Borough County sits in USDA Zone 7a. Lobelia grows reliably in zones 3a through 9b, so it's a good fit here.
Can Lobelia grow in Juneau City and Borough County's climate?
Yes — Lobelia grows well in Juneau City and Borough County's temperate climate. Juneau City and Borough County averages a 152-day frost-free season, with last frost around May 3 and first frost around October 2.
Your Juneau City and Borough Garden Planner — Free
A 22-page printable planner built for Juneau City and Borough (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.